The invention relates to a device for cooling a metering module, in particular for metering a reducing agent, such as urea or a urea/water solution, into the exhaust gas section of an internal combustion engine.
DE 44 36 397 A1 relates to a device for the aftertreatment of exhaust gases. A device for the aftertreatment of exhaust gases of a compression-ignition internal combustion engine is disclosed, in which device a reducing agent is fed into the exhaust gas which is supplied to a reducing catalytic converter in order to improve the functioning of the catalytic converter. Here, the feeding of the reducing agent takes place via an electrically controlled metering valve which is arranged in a common housing with a control valve. The control valve serves for the controlled introduction of fed compressed air, during which introduction a quantity of reducing agent which is advanced via the metering valve is prepared and is introduced intermittently into the exhaust gas. Said intermittent introduction serves, in particular, to avoid urea deposits and to avoid agglutinations on the metering valve and control valve in addition to the optimum preparation of the introduced reducing agent.
The subject matter of US 2006 0108443 A1 is a lance-shaped spraying device for a reducing agent for lowering the NOx emissions. The spraying device comprises a line for a reducing agent, in particular a urea/water solution, which line is surrounded by an atomizer line. The atomizer line is surrounded by a tubular cooling housing which forms a jacket-shaped liquid cooling chamber. The liquid cooling chamber of jacket-shaped configuration extends over a considerable length section of the atomizer line. Liquid is fed to the liquid cooling chamber via an inlet and is discharged again via an outlet. The inlet and the outlet lie at an end of the spraying device, which end is remote from the exhaust gas pipe. The inlet has an extension pipe, with the result that the cooling liquid enters into the liquid cooling chamber at a location between the inlet and the injection end.
DE 10 2009 047 375 A1 discloses a metering module, in which a metering valve is included for metering urea into the exhaust gas section of an internal combustion engine. In order for the valve tip of the metering valve to be as close as possible to the exhaust gas flow, the valve seat for the metering valve is cooled actively in the metering module. Here, the metering module is assigned a cooling device which encloses a circumferential face of the metering module and is flowed through by a cooling liquid, a cooling fluid. This is, for example, cooling fluid which is removed from the cooling fluid circuit of a vehicle. Despite the relative proximity of the metering valve to the exhaust gas flow, the temperature in the vicinity of the outlet opening, that is to say the injection opening for the reducing agent into the exhaust gas section, does not rise above 120° C.
DE 10 2005 061 145 A1 discloses an exhaust gas aftertreatment device for the aftertreatment of exhaust gas in an exhaust gas system of an internal combustion engine. The exhaust gas aftertreatment device comprises a metering valve which is flange-connected to an exhaust gas pipe. The flange protrudes laterally at an angle from the circumferential face of the exhaust gas pipe, with the result that the heat-sensitive valve tip of the metering module is spaced apart somewhat from the exhaust gas flow. For the discharge of heat, the metering valve according to this solution is surrounded in regions by cooling fins which are produced from a material which has a high thermal conductivity. In the case of passive cooling which is shown here by way of cooling fins, more advantageous closer positioning of the metering valve in relation to the exhaust gas duct is not possible for reasons of space.